(1) Field of the Invention
This invention relates to a tractor self-propelled implement vehicle or the like (hereinafter called "a tractor"). The invention is also directed to a power-module which can be used with such tractors or implements.
(2) Description of the Prior Art
The conventional tractor has been in use in the same general configuration for many years and in principle has been confined to one module incorporating the chassis, engine, transmission and operator's platform, the module being supported on four or more wheels, of which generally 2 or 4 are driven. The evolution of the tractor was based on horse drawn equipment through to the "iron horse" with implements, attachments and harvesters, the tractor taking over the role of the horse(s) as the means of motive power.
While no one will deny that the tractor has been a marked improvement over the horse in terms of productivity, expense, running costs and ease of use, the conventional tractor has limitations in many aspects and some of the more important are listed as follows:
(a) It has only one three-point linkage assembly at the rear.
(b) It requires a headland to turn about, the size of the headland depending on whether the implement is attached to the three-point linkage or to the draw bar.
(c) As the implement is generally trailed, the operator must drive looking forward to steer and rearward to control the operation of the implement.
(d) In certain applications, e.g. harvesting, separate operators are required for the tractor and implement.
(e) It is inefficient at low speeds as the engine speed, and therefore the torque and power output, is low with the possibility of the engine stalling. In addition the output speed of any drive to any implement (e.g. by the power-take-off (P.T.O.)) is not independent of the engine speed.
(f) It has not been possible to offer both high clearance and low clearance facilities on the one tractor.
(g) The extent of variations in the track, e.g. to suit row crops, has been limited, and the wheel-base has been fixed.
(h) It is liable to roll over either under load or when travelling on steep terrain.
(i) The number of attachments which can be fitted in one operation is limited.
(j) It is not adapted for quick disassembly and "walk out" from one implement for fitting to another for a second operation.
(k) It has not been convertable to an independent transporter and cannot provide the facility of a transporter e.g. during harvesting a crop.
(l) It is not readily adaptable to the fitting of implements within its wheelbase.
(m) It is not able to provide a forward speed which is slow enough to suit specific operations, e.g. mushroom compost turning.
(n) It has not been suitable as a mobile workshop with the facility to supply drive to a number of independent pieces of machinery and equipment and is not connectable to both the mechanical and/or hydraulic drive of commercially available equipment without the requirement for auxiliary power being generated by further attachments on the tractor or equipment.
(o) It has not provided an alternative range and power and type of engine for a single tractor.
(p) It has not always offered a high gear ratio for road transport and a low gear ratio for field work.
(q) It has not provided the facility to tip a transporter bin inside the four wheels or to high clear with such a bin.
(r) It has not provided the option of four wheel drive which may be fitted to a standard unit after delivery or for independent drive to the four wheels.
(s) It has not been adaptable to be packed down into a small volume module for transportation.
(t) It has not provided an all-purpose tractor powered by an all-hydrostatic power system.